[RFC PATCH 22/32] function_graph: Add a new entry handler with parent_ip and ftrace_regs

Masami Hiramatsu (Google)
2023-11-05T16:11:16Z

From: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Add a new entry handler to fgraph_ops as 'entryregfunc' which takes
parent_ip and ftrace_regs. Note that the 'entryfunc' and 'entryregfunc'
are mutual exclusive. You can set only one of them.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
arch/arm64/kernel/ftrace.c | 8 ++++-
arch/loongarch/kernel/ftrace_dyn.c | 6 +++-
arch/powerpc/kernel/trace/ftrace.c | 2 +
arch/powerpc/kernel/trace/ftrace_64_pg.c | 10 ++++--
arch/x86/kernel/ftrace.c | 50 ++++++++++++++++++++----------
include/linux/ftrace.h | 17 +++++++++-
kernel/trace/fgraph.c | 27 +++++++++++++---
7 files changed, 90 insertions(+), 30 deletions(-)

diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index a650f5e11fc5..e94d9dc13d89 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -481,7 +481,13 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs)
{
- prepare_ftrace_return(ip, &fregs->lr, fregs->fp);
+ if (unlikely(atomic_read(&current->tracing_graph_pause)))
+ return;
+
+ if (!function_graph_enter_regs(fregs->lr, ip, fregs->fp,
+ (void *)fregs->fp, fregs)) {
+ fregs->lr = (unsigned long)&return_to_handler;
+ }
}
#else
/*
diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c
index 73858c9029cc..39b3f09a5e0c 100644
--- a/arch/loongarch/kernel/ftrace_dyn.c
+++ b/arch/loongarch/kernel/ftrace_dyn.c
@@ -244,7 +244,11 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct pt_regs *regs = &fregs->regs;
unsigned long *parent = (unsigned long *)&regs->regs[1];

- prepare_ftrace_return(ip, (unsigned long *)parent);
+ if (unlikely(atomic_read(&current->tracing_graph_pause)))
+ return;
+
+ if (!function_graph_enter_regs(regs->regs[1], ip, 0, parent, fregs))
+ regs->regs[1] = (unsigned long)&return_to_handler;
}
#else
static int ftrace_modify_graph_caller(bool enable)
diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index 82010629cf88..9bf1b6912116 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -422,7 +422,7 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
if (bit < 0)
goto out;

- if (!function_graph_enter(parent_ip, ip, 0, (unsigned long *)sp))
+ if (!function_graph_enter_regs(parent_ip, ip, 0, (unsigned long *)sp, fregs))
parent_ip = ppc_function_entry(return_to_handler);

ftrace_test_recursion_unlock(bit);
diff --git a/arch/powerpc/kernel/trace/ftrace_64_pg.c b/arch/powerpc/kernel/trace/ftrace_64_pg.c
index 7b85c3b460a3..43f6cfaaf7db 100644
--- a/arch/powerpc/kernel/trace/ftrace_64_pg.c
+++ b/arch/powerpc/kernel/trace/ftrace_64_pg.c
@@ -795,7 +795,8 @@ int ftrace_disable_ftrace_graph_caller(void)
* in current thread info. Return the address we want to divert to.
*/
static unsigned long
-__prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp)
+__prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp,
+ struct ftrace_regs *fregs)
{
unsigned long return_hooker;
int bit;
@@ -812,7 +813,7 @@ __prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp

return_hooker = ppc_function_entry(return_to_handler);

- if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp))
+ if (!function_graph_enter_regs(parent, ip, 0, (unsigned long *)sp, fregs))
parent = return_hooker;

ftrace_test_recursion_unlock(bit);
@@ -824,13 +825,14 @@ __prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs)
{
- fregs->regs.link = __prepare_ftrace_return(parent_ip, ip, fregs->regs.gpr[1]);
+ fregs->regs.link = __prepare_ftrace_return(parent_ip, ip,
+ fregs->regs.gpr[1], fregs);
}
#else
unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
unsigned long sp)
{
- return __prepare_ftrace_return(parent, ip, sp);
+ return __prepare_ftrace_return(parent, ip, sp, NULL);
}
#endif
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 12df54ff0e81..85247a8f265b 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -614,16 +614,8 @@ int ftrace_disable_ftrace_graph_caller(void)
}
#endif /* CONFIG_DYNAMIC_FTRACE && !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */

-/*
- * Hook the return address and push it in the stack of return addrs
- * in current thread info.
- */
-void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
- unsigned long frame_pointer)
+static inline bool skip_ftrace_return(void)
{
- unsigned long return_hooker = (unsigned long)&return_to_handler;
- int bit;
-
/*
* When resuming from suspend-to-ram, this function can be indirectly
* called from early CPU startup code while the CPU is in real mode,
@@ -633,13 +625,28 @@ void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
* This check isn't as accurate as virt_addr_valid(), but it should be
* good enough for this purpose, and it's fast.
*/
- if (unlikely((long)__builtin_frame_address(0) >= 0))
- return;
+ if ((long)__builtin_frame_address(0) >= 0)
+ return true;

- if (unlikely(ftrace_graph_is_dead()))
- return;
+ if (ftrace_graph_is_dead())
+ return true;
+
+ if (atomic_read(&current->tracing_graph_pause))
+ return true;
+ return false;
+}
+
+/*
+ * Hook the return address and push it in the stack of return addrs
+ * in current thread info.
+ */
+void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
+ unsigned long frame_pointer)
+{
+ unsigned long return_hooker = (unsigned long)&return_to_handler;
+ int bit;

- if (unlikely(atomic_read(&current->tracing_graph_pause)))
+ if (unlikely(skip_ftrace_return()))
return;

bit = ftrace_test_recursion_trylock(ip, *parent);
@@ -657,9 +664,20 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs)
{
struct pt_regs *regs = &fregs->regs;
- unsigned long *stack = (unsigned long *)kernel_stack_pointer(regs);
+ unsigned long *parent = (unsigned long *)kernel_stack_pointer(regs);
+ int bit;

- prepare_ftrace_return(ip, (unsigned long *)stack, 0);
+ if (unlikely(skip_ftrace_return()))
+ return;
+
+ bit = ftrace_test_recursion_trylock(ip, *parent);
+ if (bit < 0)
+ return;
+
+ if (!function_graph_enter_regs(*parent, ip, 0, parent, fregs))
+ *parent = (unsigned long)&return_to_handler;
+
+ ftrace_test_recursion_unlock(bit);
}
#endif

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 2e24a2611ca8..a6fd930d3500 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1037,6 +1037,11 @@ typedef void (*trace_func_graph_ret_t)(struct ftrace_graph_ret *,
typedef int (*trace_func_graph_ent_t)(struct ftrace_graph_ent *,
struct fgraph_ops *); /* entry */

+typedef int (*trace_func_graph_regs_ent_t)(unsigned long func,
+ unsigned long parent_ip,
+ struct ftrace_regs *fregs,
+ struct fgraph_ops *); /* entry w/ regs */
+
extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph_ops *gops);

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
@@ -1044,6 +1049,7 @@ extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph
struct fgraph_ops {
trace_func_graph_ent_t entryfunc;
trace_func_graph_ret_t retfunc;
+ trace_func_graph_regs_ent_t entryregfunc;
struct ftrace_ops ops; /* for the hash lists */
void *private;
int idx;
@@ -1080,8 +1086,15 @@ struct ftrace_ret_stack {
extern void return_to_handler(void);

extern int
-function_graph_enter(unsigned long ret, unsigned long func,
- unsigned long frame_pointer, unsigned long *retp);
+function_graph_enter_regs(unsigned long ret, unsigned long func,
+ unsigned long frame_pointer, unsigned long *retp,
+ struct ftrace_regs *fregs);
+
+static inline int function_graph_enter(unsigned long ret, unsigned long func,
+ unsigned long fp, unsigned long *retp)
+{
+ return function_graph_enter_regs(ret, func, fp, retp, NULL);
+}

struct ftrace_ret_stack *
ftrace_graph_get_ret_stack(struct task_struct *task, int idx);
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index e7188c67356e..2623a5987f52 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -512,8 +512,20 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
# define MCOUNT_INSN_SIZE 0
#endif

-int function_graph_enter(unsigned long ret, unsigned long func,
- unsigned long frame_pointer, unsigned long *retp)
+static inline int call_entry_func(struct ftrace_graph_ent *trace,
+ unsigned long func, unsigned long ret,
+ struct ftrace_regs *fregs,
+ struct fgraph_ops *gops)
+{
+ if (gops->entryregfunc)
+ return gops->entryregfunc(func, ret, fregs, gops);
+
+ return gops->entryfunc(trace, gops);
+}
+
+int function_graph_enter_regs(unsigned long ret, unsigned long func,
+ unsigned long frame_pointer, unsigned long *retp,
+ struct ftrace_regs *fregs)
{
struct ftrace_graph_ent trace;
int save_curr_ret_stack;
@@ -558,7 +570,7 @@ int function_graph_enter(unsigned long ret, unsigned long func,
}
save_curr_ret_stack = current->curr_ret_stack;
if (ftrace_ops_test(&gops->ops, func, NULL) &&
- gops->entryfunc(&trace, gops)) {
+ call_entry_func(&trace, func, ret, fregs, gops)) {
/* Note, curr_ret_stack could change by enryfunc() */
offset = current->curr_ret_stack;
/* Check the top level stored word */
@@ -876,7 +888,8 @@ void fgraph_init_ops(struct ftrace_ops *dst_ops,
struct ftrace_ops *src_ops)
{
dst_ops->func = ftrace_graph_func;
- dst_ops->flags = FTRACE_OPS_FL_PID | FTRACE_OPS_FL_STUB;
+ dst_ops->flags = FTRACE_OPS_FL_PID | FTRACE_OPS_FL_STUB |
+ FTRACE_OPS_FL_SAVE_ARGS;

#ifdef FTRACE_GRAPH_TRAMP_ADDR
dst_ops->trampoline = FTRACE_GRAPH_TRAMP_ADDR;
@@ -1119,10 +1132,14 @@ int register_ftrace_graph(struct fgraph_ops *gops)
int ret = 0;
int i;

+ if (gops->entryfunc && gops->entryregfunc)
+ return -EINVAL;
+
mutex_lock(&ftrace_lock);

if (!gops->ops.func) {
- gops->ops.flags |= FTRACE_OPS_FL_STUB;
+ gops->ops.flags |=
+ FTRACE_OPS_FL_STUB | FTRACE_OPS_FL_SAVE_ARGS;
gops->ops.func = ftrace_graph_func;
#ifdef FTRACE_GRAPH_TRAMP_ADDR
gops->ops.trampoline = FTRACE_GRAPH_TRAMP_ADDR;